Bella and Ken from Orange, Connecticut, had been married five years and were raising two young daughters when Bella met Daniel at a party, and sparks flew.

“At the end of the night, I don’t know why but he was about to leave and we were saying goodbye, and I kissed him,” Bella, 34, told Barcroft TV.

“I was like, ‘okay, I’m married and I just kissed another married man’. I was having very conflicted feelings about it, but I wanted to do it again.”

Though the college sweethearts were strictly monogamous, they discussed exploring having other partners and decided to get to know Daniel and his wife – who were in an open relationship – better.

Bella, 34, said: “There was a lot of chemistry and we were like ‘maybe this is something that we really want to try’, so we invited them over, we talked a couple of times and we ended up all having sex, and we kind of went from there.”

Ken, 38, said: “It was a lot of rotating pairs most of the time.”

But before long, cracks started to show in Daniel and his wife’s relationship.

Daniel, 33, said: “So her and I were together for a long time, and we had problems well before Bella and Ken came along.

“Unfortunately, something that I think polyamory does very well is that it highlights everything, and you end up talking about things that might have been pushed under the rug previously.”

In 2015, a year after the foursome had their first encounter, Daniel and his wife divorced, and the next step for Ken, Bella and Daniel seemed natural to them.

Bella said: “We were like ‘okay, well you can live with us now’!”

The newly formed throuple moved into a new, larger house together, and settled into a king size bed that all three share, and established their three-way bedroom dynamic.

Daniel said: “It’s usually the two of us, or the two of them, generally.”

Bella said: “It’s actually not very often that the three of us are together sexually.”

Though sometimes, the two men will become intimate.

Daniel said: “It’s an uncommon thing. It’s like cake – you don’t have cake all the time.”

Two years ago, Ken became involved with Laura, his own girlfriend who also has two children.

Ken said: “Laura is wonderful. She’s not involved with Bella or Daniel. She and I are involved and that’s her attachment to us.”

Daniel works as a magician, and Bella joined him as his assistant, often travelling out of state to perform fire-handling as part of his act.

On jealousy within poly relationships, the group swear by communicating their feelings.

Ken said: “If you ignore it, it will breed resentment, and if you talk about it and you deal with it then maybe you can find the root cause and get past it.

“I don’t know if it’s harder, it just means we need to talk about things more than sometimes you do when there is only one other person.”

As parents, when Daniel moved in, Bella and Ken had to explain it to their then three- and four-year-old daughters.

Ken said: “They were really happy with it, and now they don’t remember before that. We share the responsibilities of parenting – parenting together in our own various styles and on the same team.”

Bella said: “The girls were playing with one of their friends and the friend kind of remarked to our little one saying ‘you have two dads and a mom’ and she said ‘yeah, some people have two dads, and that’s okay’.”

Daniel said: “I never wanted to have children because I always worried about my lifestyle being too selfish for children, like that I would be travelling all over the place and bringing kids with you is a big problem especially when they are little.

“So to have this situation where I can love these two girls and be a parent, but when I’m not there I know that they are taken care of and I’m not leaving one person at home to take care of all the duties is really nice and really comforting.”

Bella and Ken’s daughter Aurelie, seven, said: “My favourite thing about my first dad is that he likes to write books and I like to write books, and the thing about my other dad is that I like to do magic and he does magic.”